Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2024	Apr. 30, 2023	Apr. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 23.9	$ 25.6	$ 22.3
Related income tax benefit	5.6	6.0	5.3
Selling, Distribution And Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	23.7	25.6	23.7
Other special project costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 0.2	$ 0.0	$ (1.4)